In cases in which there is a great distance between the entrance of the building and the location of the fire, autonomous air units are employed for breathing, as protection against the toxic fumes produced by combustion. These autonomous air units consist of compressed air bottles that provide air for a limited time. Therefore, a limited time is available to locate the fire and then reach the exit of the building.
An added hazard to work in risky conditions is the difficulty of communication with the exterior. Furthermore, there are no points of reference of the path followed and it is possible to become disoriented and be lost when trying to find the exit, as the work is performed in an unfamiliar place without illumination. Yet another disadvantage is that vision is severely impaired by the fumes.
The only control system for workers who work in risky conditions currently available consists of a table and a board. The safety manager located outside the building or area involved notes the workers and time of entry in the building on the board. Any fire fighter entering the premises, tunnel or underground train must hand in a personal badge to the safety manager. The latter will insert this badge in grooves made in the board and note its time of delivery. When the fire fighter exits the badge is returned to him or her. This system allows knowing the number of persons and time of permanence inside the building, premises, garage, tunnel, etc.
Another existing safety element consists of a pressure gauge coupled to the air bottle used to breathe in contaminated atmospheres. These pressure gauges indicate the air pressure inside the bottle and the remaining breathing time. They also indicate the external temperature and include a dead-man alarm. This information is not communicated to the exterior.
Currently, the demand for controlling workers working in risky conditions is not met as relates to their state and location. Also not resolved is the problem of communication with the exterior of the workers working inside buildings, basements, garages or tunnels.